Currently cobalt based alloys are used in the steam generating plant of nuclear reactors, but cobalt has a long half life making the use of cobalt undesirable for use in such applications. Some known iron base alloys have good wear properties, but insufficient corrosion resistance. Some known nickel base alloys have good corrosion resistance but poor wear resistance.
One known stainless steel potentially suitable for use in components of nuclear reactors is disclosed in UK patent 2167088, and this comprises broadly speaking 15 to less than 25 wt % chromium, 5 to 15 wt % nickel, 2.7 to 5.5 wt % silicon, 1 to 3 wt % carbon, 5 to 15 wt % niobium plus vanadium, up to 0.15 wt % nitrogen, up to 1.5 wt % cobalt and the balance iron plus impurities. This alloy contains very little or no cobalt thus having a low half life.
The particular stainless steel alloy available commercially from Deloro Stellite, St Louis, Mo. USA under the trade name Tristelle 5183, comprises in weight percent 19-22 chromium, 8.5 to 10.5 nickel, 4.5 to 5.5 silicon, 6.5 to 7.5 niobium, 1.8 to 2.2 carbon, up to 0.1 nitrogen and balance iron plus impurities.
The alloys suitable for use in steam generating plant of nuclear reactors must have high wear resistance and high corrosion resistance. The alloys disclosed in UK patent 2167088 have been tested and it has been found that they have a hardness of 350-450 Vickers (38-44 Rockwell C performed on a Rockwell hardness testing machine).